The basic purpose of Acts is to portray the development of the Christian movement in its first three decades. There are four interlocking phases in this development.
1. The movement from Jews to Gentiles. This phase contains initial outreach to the Jews (1:1-8:3); outreach to “second-class” Jews, such as Samaritans and proselytes (8:4-40); outreach to God-fearing Gentiles (9:32-11:18); finally, outreach to Gentiles with no connection to Judaism (13:2-21:15).
2. The movement from Jerusalem to Rome. This movement also has four stages: (1) from Jerusalem throughout Judea, Samaria, and Galilee (1:1-9:31); (2) extension to Antioch (11:19-13:1); (3) the Antioch-based mission (13:2-21:16); (4) Paul to Rome (21:17-28:31).
3. The problems within the Christian movement. There are four dimensions to these problems that thread through the book: (1) Jews versus Jewish Christians, (2) Hebrew Christians versus Hellenistic Christians, (3) Jewish Christians versus gentile Christians, (4) Christians versus Roman authorities.
4. The establishment of Paul's primacy in the emergence of Christianity out of Judaism into the Roman world. One way in which the author establishes Paul's authority is to select events from Paul's ministry to the Gentiles that parallel Peter's ministry to the Jews. Each heals a lame person (3:2-10; 14:8-10), each is the source of miraculous healings (5:15; 19:12), each performs exorcisms (5:16; 16:18), each contends with sorcerers (8:18-24; 13:6-11), each raises the dead (9:36-42; 20:9-10?), and each has miraculous deliverances from prison (5:19: 12:7-11; 16:25-26).
The author skillfully interweaves these four phases to record how, through the empowerment and guidance of the Holy Spirit, a small Jewish, messianic sect became a major movement in the Roman world.